1. Field of the Invention
The present invention relates to a printing apparatus and a printing control method, and specifically to a printing apparatus and a printing control method that can perform printing on both surfaces of a continuous sheet.
2. Description of the Related Art
Conventionally a continuous sheet such as a roll paper is produced by establishing connections between sheets. The continuous sheet has a splice portion caused by this connection process, and the splice portion is generally inappropriate for printing. In addition, also in a case where damages exist on the sheet, the damage becomes a spot inappropriate for printing. In general, in a case of using the continuous sheet on which these unique portions that are inappropriate for printing exist, the control of avoiding the unique portion to perform printing is performed. This control allows the continuous sheet on which the unique portion exists to be used for printing and reduces the waste of the sheet. It should be noted that in the present specification, the unique portion means a portion where a characteristic of a sheet partially differs, such as a blot, a hole and a damage in a sheet, a splice portion between sheets, a fracture and a break in a sheet, foreign object mixing to a sheet, a change in color, unevenness in thickness and a dirt in a sheet, and the like.
Japanese Patent Laid-Open No. 2011-240493 discloses a technique that in a case of performing printing on both surfaces of the continuous sheet on which the unique portion exists, when the unique portion is detected during performing the printing on one side surface (front surface) of the sheet, the printing onto the detected spot is avoided and the printing avoided image is printed on the next printable area. In addition, in Japanese Patent Laid-Open No. 2011-240493, the printing is controlled such that printing to a region of other side surface corresponding to the spot of the one side surface in which the unique portion is detected is likewise avoided and the printing avoided image is printed in the next region. This control allows the printing to be performed on both of the one side surface and the other side surface of the sheet while avoiding the spot where the unique portion exists, thus preventing generation of defect printing.
However, Japanese Patent Laid-Open No. 2011-240493 does not describe at all a case where the unique portion exists on the other side surface of the sheet. That is, according to Japanese Patent Laid-Open No. 2011-240493, detection of the unique portion is not performed in the printing onto the other side surface of the sheet and, as described above, the printing onto the area corresponding to the unique portion detection on the one side surface is only avoided. Therefore the printing is performed as it is even if the unique portion exists on the other side surface. In this case, there occurs a problem that a quality of the printed image is degraded due to the existence of the unique portion. In addition, in a case of a set of images associated on the front and other side surfaces as in the case of bookbinding of a photo book or the like, the printed image on the one side surface corresponding to the other side surface on which the unique portion exists becomes wasteful.